Documentation

renameFile old new changes the name of an existing file system
object from old to new. If the new object already
exists, it is atomically replaced by the old object. Neither
path may refer to an existing directory. A conformant implementation
need not support renaming files in all situations (e.g. renaming
across different physical devices), but the constraints must be
documented.

The operation may fail with:

HardwareFault
A physical I/O error has occurred.
[EIO]

InvalidArgument
Either operand is not a valid file name.
[ENAMETOOLONG, ELOOP]

isDoesNotExistError / NoSuchThing
The original file does not exist, or there is no path to the target.
[ENOENT, ENOTDIR]

installHandler int handler iset calls sigaction to install an
interrupt handler for signal int. If handler is Default,
SIG_DFL is installed; if handler is Ignore, SIG_IGN is
installed; if handler is Catch action, a handler is installed
which will invoke action in a new thread when (or shortly after) the
signal is received.
If iset is Just s, then the sa_mask of the sigaction structure
is set to s; otherwise it is cleared. The previously installed
signal handler for int is returned